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Primare Knob

How to handle multi Subwoofer setup

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1 minute ago, Primare Knob said:

What would the suggestion be for subwoofer placement? Technicly my front speakers go down to 29Hz -3dB

Both in the front of the room.

Both in the front corners of the room

One in the front one in the back

Both in the back of the room

Placement is irrelevant the way I see it with whatever tools you use.

Good/best placement is an advantage regardless of what tools you use.

FWIW I placed mine in the front corners with an 80Hz crossover.

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5 minutes ago, Primare Knob said:

 

What would the suggestion be for subwoofer placement? Technicly my front speakers go down to 29Hz -3dB

Both in the front of the room.

Both in the front corners of the room

One in the front one in the back

Both in the back of the room

Have you measured them inroom ? With a quoted 29hz if legit in room should easily be 20hz or lower so worth measuring. But also will mean more effort in integration 

 

placement of sub is supreme importance again here if have measured where work best will have your answer :)

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2 minutes ago, Primare Knob said:

Can't it do the same with a single channel? Or will this not work with integrating the low end of the front speakers. I would like to bypass any AD for non LFE/Low end frequency.

It can do the same with a single channel. But then you're probably not really integrating the front speakers.

And the MiniDSP 2X4HD as an optical input by the way although I firmly believe an AD conversion via analog inputs is nothing to worry about.

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2 minutes ago, Satanica said:

It can do the same with a single channel. But then you're probably not really integrating the front speakers.

And the MiniDSP 2X4HD as an optical input by the way although I firmly believe an AD conversion via analog inputs is nothing to worry about.

Have to try the record Toslink output of the PrePro and see what it spits out, since it can't do any 8 channel HD formats. But the miniDSP is looking like my best option anyway.

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An excellent side effect which I was not expecting of turning frequencies under 80Hz into a mono signal for dual subwoofers rather then stereo subwoofers is that it cleared up rattle noises in and outside the house.

Proper time alignment may have helped with this too.

But I don't really have the technical knowledge to understand the big reduction in house vibrations and rattle sounds.

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24 minutes ago, Satanica said:

An excellent side effect which I was not expecting of turning frequencies under 80Hz into a mono signal for dual subwoofers rather then stereo subwoofers is that it cleared up rattle noises in and outside the house.

Proper time alignment may have helped with this too.

But I don't really have the technical knowledge to understand the big reduction in house vibrations and rattle sounds.

Would most likely be a reduction of excited room modes, that may have resonated with the windows, usually around 30hz

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If you are considering using a Mini-DSP, then have a look at this:

I used MSO to optimise my dual subs for both the HT and 2 channel setups. 

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The guys have given some really good tips here. 

Overall if I could throw my coin into the mix I'd be mindful of your main/sub and LFE crossover point. 

Regardless of cone size of the bass drivers in your main speakers remember the LFE channel is meant to be 10dB higher than all other channels. 

Reason why 80hz is a general standard is it helps retain impact across the bass spectrum issued to the LFE channel. Your 10" drivers in your mains no doubt can do 29,30,50hz etc but they won't be +10dB in that region. 

In movies there is a lot of punch and thud area between 55and 120hz. So you don't want to deprive your overall listening experience missing out on the region by crossing over your LFE at say 40hz or even your mains at 40hz... 

My mains have 15" bass drivers and they are processed full range (Large) however my LFE is crossed at 80hz and it does not sound right set any lower 

 

Hope that helps

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1 hour ago, Neilsy said:

My mains have 15" bass drivers and they are processed full range (Large)...

Huge for any main speaker, what are they?

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I'll have to get back to this after the holidays. Might as well order the miniDSP and bring some reading material so I can start on this once I am back.

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2 hours ago, Neilsy said:

The guys have given some really good tips here. 

Overall if I could throw my coin into the mix I'd be mindful of your main/sub and LFE crossover point. 

Regardless of cone size of the bass drivers in your main speakers remember the LFE channel is meant to be 10dB higher than all other channels. 

Reason why 80hz is a general standard is it helps retain impact across the bass spectrum issued to the LFE channel. Your 10" drivers in your mains no doubt can do 29,30,50hz etc but they won't be +10dB in that region. 

In movies there is a lot of punch and thud area between 55and 120hz. So you don't want to deprive your overall listening experience missing out on the region by crossing over your LFE at say 40hz or even your mains at 40hz... 

My mains have 15" bass drivers and they are processed full range (Large) however my LFE is crossed at 80hz and it does not sound right set any lower 

 

Hope that helps

one of the reasons I would be still suggesting a LFE channel be maintained. by all means make mains full range. but no need for them to be doing LFE for very reasons you mentioned. and I would be crossing the LFE channel at 80hz as well. the dedicated LFE channel which is there for most mixes tends to have info right upto 120hz however further up there is going to be no bother for most speakers to achieve :)

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10 minutes ago, :) al said:

one of the reasons I would be still suggesting a LFE channel be maintained. by all means make mains full range. but no need for them to be doing LFE for very reasons you mentioned. and I would be crossing the LFE channel at 80hz as well. the dedicated LFE channel which is there for most mixes tends to have info right upto 120hz however further up there is going to be no bother for most speakers to achieve :)

Or you could just mix the LFE into the Left and Right Channels and crossover to the subs at 80Hz.

This method will increase your system's headroom, no longer do the mains have to bother themselves with the really low stuff.

Edited by Satanica

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On 19/10/2017 at 2:42 PM, Satanica said:

Huge for any main speaker, what are they?

Sorry slow reply..  They are Krix Theatrix 

http://www.krix.com.au/theatrix/

 

15" bass/mid up to 400hz, external managed crossover to 

6.5" horn loaded mid, then built in crossover to compression driver for highs, again horn loaded. Serves L, C, R behind my AT screen

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I have settled for my subwoofer placement and I used the "golden ratio" 1:1'618

It might be a bit unorthodox, but this seems to produce the best result by ear. I tried the 1/4 room width placement but the subs have 2 passive radiators which when placed in line with each other produces some rumbling side effects. When placed in line with the speaker smack bang against the wall, the radiator facing the wall is producing some rumbling and harsh side effects.

There is still a lot of work to do. Masters and Commanders the canon's scene sound rather good, but the Start Trek intro is nothing but unpleasant rumbling of noise.b9e49e3055914ca6c6a4c38444437748.jpg

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As a recap to get a better understanding before I dig in.

If my subs are placed at equal distance from my LP, that doesn't automatically mean that their signal are time aligned?

The only thing that could this is a miniDSP or a Processor that can set induvidual timing on two subs?

If time alignment happens to be within limits would I need the miniDSP if I:
Only looking at integrating subs with movies.
Have the ability to software EQ each individual sub and adjust level and phase. (PBK kit)
Can software EQ both subs together. (REW /JRiver)

To integrate two subs with my mains I would automatically look at a miniDSP or a processor that can handle 2 individual subs and set high pass filters?

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19 hours ago, Primare Knob said:

As a recap to get a better understanding before I dig in.

If my subs are placed at equal distance from my LP, that doesn't automatically mean that their signal are time aligned?

The only thing that could this is a miniDSP or a Processor that can set induvidual timing on two subs?

If time alignment happens to be within limits would I need the miniDSP if I:
Only looking at integrating subs with movies.
Have the ability to software EQ each individual sub and adjust level and phase. (PBK kit)
Can software EQ both subs together. (REW /JRiver)

To integrate two subs with my mains I would automatically look at a miniDSP or a processor that can handle 2 individual subs and set high pass filters?

If two subs were exactly the same distance from the listening position then I think they're time aligned. That's how mine have measured. 

 

MiniDSP will do the job for you. 

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On 11/17/2017 at 2:20 PM, Primare Knob said:

If my subs are placed at equal distance from my LP, that doesn't automatically mean that their signal are time aligned?

Not necessarily. A sub sitting right next to a woofer could be lagging behind due to the acoustic low pass filter. In some cases, they won't even be close.

 

Mini DSP have some great tools for calibrating subs.

 

The best positions for subs tends to vary based on the room, available positions, the location of chairs and the priority given to different seats. Harman configurations tend to work well for simple rectangular rooms where your main goal is avoiding seat to seat variation. In the more common situation where one prime seat is the priority (most say that when I ask), there are usually one or two specific locations that work out better.

 

If you aren't determined to have stereo subs, then it can work out simpler to set mains to small and cross to the subs at 80 Hz. With MiniDSP you can take one LFE output and EQ the subs either as if they were one or individually. Individual calibration does have advantages.

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I have made some progress but still are a long way off from understanding.

I have started using REW and a calibrated measurement mic. In REW I played around with the room simulation, and it showed why my subs in that particular position solved some problems, it also showed me what other problems that position was causing, (very low output in 60-80hz) and after mucking around I decided that the 1/4 position along the front wall was the least worse, and would produce good output.

I also found that my subs were set to loud, as it seems that my SPL meter is very bad in picking up low frequencies, compared to the microphone.

I did some measurements and started tuning both subs using the left and right output together when doing sweeps in REW and using parametric equaliser in JRiver to flatten the response.

I have started doing this for the 20-200Hz range of my front speakers as well.

I does work to some extend as seems to have made sound stage clearer and more articulated, and fixed most of the room nodes, I don't think this is the best way to go about it and doesn't seem to be the most consistent.

Ill still have to work out cross over settings and where to use them. In JRiver or in the Pre Pro. As I can't bypass the cross over in the Pre Pro unless if I lose the LFE channel. I have set the cross over in the Pre Pro at 40Hz and the sub to 200Hz, but now I have to eq the subs again to integrate them with the fronts crossed over at 60 or 80Hz. Everything messed up again.

I haven't started on the MiniDSP yet as I like to avoid doubeling up on the AD DA process as my Subs and Front Speaker already do that as well. Or I might need some time to get used to the idea, as my speakers and subs already do this and it never bothered me.

The other idea I am playing with is to buy a 8+ channel DAC and get rid of the Pre Pro completely.

All things that are new territory for me and scares the **** out of me.

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On 04/01/2018 at 6:52 PM, Primare Knob said:

"... it also showed me what other problems that position was causing, (very low output in 60-80hz).." 

"I also found that my subs were set to loud, as it seems that my SPL meter is very bad in picking up low frequencies, compared to the microphone."

I have started doing this for the 20-200Hz range of my front speakers as well.

"... As I can't bypass the cross over in the Pre Pro unless if I lose the LFE channel. I have set the cross over in the Pre Pro at 40Hz and the sub to 200Hz, but now I have to eq the subs again to integrate them with the fronts crossed over at 60 or 80Hz. Everything messed up again... "

Apologies if any of this has already been addressed, but here's some points that may help:

 

1. Low output 60-80hz sounds like there is still too low of a crossover engaged. With your pre pro you mentioned 40hz, if that is for the LFE channel I'd try it set up at at 80hz and then disengage any high pass filter on the subs, if possible, or set as high as you can (like 200hz).

 

2. It's not always perfect getting the bass right as SPL and dB meters use averages but not linearly down to the full spectrum of 20hz. I'd run noise through your main channels set to 75dB on the dB meter, C-weighted, and have the subs read about 82dB, it should account for the subsonic loss. 

 

3. Always consider the LFE an isolated channel. Even if you set a differing crossover from your, say, left & right speakers (60hz e.g.) your LFE should always be 80hz due to what will get sent down the dedicated LFE channel. 

Another thing, be careful with what noise you tune your system with - - if it's pink noise from a CD it is likely to be in 2.0 meaning tuning your subwoofer from this will be completely inaccurate especially if you have set a low crossover for your fronts such as 40 or 60hz, as that's all the subs will get. 

 

Hope some of that helps. Let me know if any Qs

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On 1/9/2018 at 10:13 AM, Neilsy said:

Apologies if any of this has already been addressed, but here's some points that may help:

 

1. Low output 60-80hz sounds like there is still too low of a crossover engaged. With your pre pro you mentioned 40hz, if that is for the LFE channel I'd try it set up at at 80hz and then disengage any high pass filter on the subs, if possible, or set as high as you can (like 200hz).

 

2. It's not always perfect getting the bass right as SPL and dB meters use averages but not linearly down to the full spectrum of 20hz. I'd run noise through your main channels set to 75dB on the dB meter, C-weighted, and have the subs read about 82dB, it should account for the subsonic loss. 

 

3. Always consider the LFE an isolated channel. Even if you set a differing crossover from your, say, left & right speakers (60hz e.g.) your LFE should always be 80hz due to what will get sent down the dedicated LFE channel. 

Another thing, be careful with what noise you tune your system with - - if it's pink noise from a CD it is likely to be in 2.0 meaning tuning your subwoofer from this will be completely inaccurate especially if you have set a low crossover for your fronts such as 40 or 60hz, as that's all the subs will get. 

 

Hope some of that helps. Let me know if any Qs

Point 1. has to do with placement, and not so much with x-over settings. As I found out, if setting speakers to large, my PrePro seems to ignore any x-over settings.

Point 2. I have started using REW and calibrated mic to set SPL levels. Mic is definitely more accurate with LFE noise

Point 3. REW has a dedicated Sub test signal and I have also used a Calibration Blu Ray disc before REW

 

After doing some test measurements it looks like my sub are time aligned and produce no individual delays. However, they seem to be out of phase with each other for some reason. Setting one sub to a phase angle between 45 and 135 seems to fix the problem. The 90 setting is giving me the biggest SPL output.

 

How I am going to integrate them into my system is still up for debate. But it most likely is going to be integrated with the mains, as their position is producing some dips in the response. But first of all, I have some massive room issues that need to be addressed before that.

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27 minutes ago, Primare Knob said:

Point 1. has to do with placement, and not so much with x-over settings. As I found out, if setting speakers to large, my PrePro seems to ignore any x-over settings.

Point 2. I have started using REW and calibrated mic to set SPL levels. Mic is definitely more accurate with LFE noise

Point 3. REW has a dedicated Sub test signal and I have also used a Calibration Blu Ray disc before REW

 

After doing some test measurements it looks like my sub are time aligned and produce no individual delays. However, they seem to be out of phase with each other for some reason. Setting one sub to a phase angle between 45 and 135 seems to fix the problem. The 90 setting is giving me the biggest SPL output.

 

How I am going to integrate them into my system is still up for debate. But it most likely is going to be integrated with the mains, as their position is producing some dips in the response. But first of all, I have some massive room issues that need to be addressed before that.

Good to hear with REW it's easy like that. 

And yep, speakers set to Large will run them as full range - no bass sent to subs. 

Where are your subs positioned compared to your main speakers? If they are together you should only need to set delay (phase) as a combined pair. If different locations (i.e one front of room, one rear of room)  then different phase. 

In terms of correct phase, it should be set to the highest volume at the crossover point (when using bass mgt on front speakers) otherwise you may experience cancellation or combing issues

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